In the biggest single cut to the size of the army, 4,480 soldiers have been handed redundancy notices as the force aims to reduce personnel numbers to 82,000 by 2018 from more than 100,000 three years ago.

In the third of what officials described as across-the-board salami slices, the Ministry of Defence said on Tuesday that 84% of those affected had applied for redundancy.

No personnel preparing for, serving on, or recovering from deployments lost their jobs unless they applied for redundancy.

Personnel recovering from serious injuries sustained on operations were also exempt from the cuts. However, officials say staff in these categories could be made redundant in the final round of cuts next year.

Those who applied for voluntary redundancy will leave on or before 17 December, and those who did not will leave on or before 17 June 2014.

There will be no new reductions in the army as a result of the latest spending review, due to be announced by the chancellor next Wednesday. The defence secretary, Philip Hammond, has already negotiated a 1% increase in the defence equipment programme, but is having to find a 5% cut in his overall budget for 2015-16.

Danny Alexander, the chief secretary to the Treasury, showed little sympathy for the army when he said last week it had "more horses than tanks". The army has been getting rid of many of its tanks, now seen as less relevant in modern warfare.

Defence chiefs hope that the number of reservists will double to 30,000 by 2018, but whether it attains this optimistic objective will depend to a great extent on the attitude of employers. It will also depend more on private contractors.

The army says it will continue to attract new recruits – some 10,000 soldiers and officers this year – to keep a balanced rank structure and age range.

On Tuesday, General Sir Peter Wall, the head of the army, described the redundancies as "a difficult but essential step towards our army 2020 structure. We owe our sincere gratitude to those leaving the army for their service over such a demanding period of operations.

"We will support them and their families as best we can on their path to civilian life. Meanwhile we continue to need plenty of young and talented recruits to ensure the army is fit to meet the challenges of the future."

Wall warned last week that gaps between military resources and planned capabilities caused by spending cuts "could become quite dangerous, quite quickly".

He told Sky News: "We have got to the point in a number of parts in our set-up where we can't go any further without seriously damaging our professional competence and our chances of success in the battlefields of the future. It would be a brave claim to say an organisation can never make more efficiencies but we do need the time to let our new structures bed in, for those efficiencies to get delivered."

Hammond said on Tuesday: "Although smaller, our armed forces will be more flexible and agile to reflect the challenges of the future with the protection and equipment they need. They will continue to be the bedrock of our society and provide extremely rewarding and exciting careers for future recruits."

The UK's most senior officer in Afghanistan, Major Chris Braithwaite, who left the army this week after he was told a year ago he would be made redundant, said the timing meant he was 87 days short of being entitled to much better pension rights.

Braithwaite, who has served in Iraq and Afghanistan, told BBC News the government's actions were contrary to the military covenant – a promise of a duty of care in return for sacrifices made: "It's a real feeling of being let down; it's a bond of trust between the armed forces and the nation, the military covenant."

The RAF and Royal Navy have already cut their numbers by 5,000 each and have no plans to make further cuts.